Turbo 400 VSS conversion for cheap for the RetroC10?

[RetroC10Sport]

Okay, I am a good mechanic and electrician but not savvy on transmissions as some of you - HotRod and Pops come to mind, maybe Jim can help too.

I have a truck T400 in my '81. I am currently running a cable speedo and I want to convert it to a 1990-91 electric speedo cheaply as I would rather use as few aftermarket parts as possible. Are there any VSS, reluctor wheel, or possibly a geared electric VSS I can find in a junkyard?

I don't need the ECM for the DRAC module since I am not running an ECM yet... But I will need the DRAC for an accurate speedo reading. The speedo will be off unless the DRAC is modified for the trans/tires/gear ratio.

[now here is where I pretty much answer my own question]
I've seen a couple of 1989-1990 T400 GMT400s at the junkyard, but from what i hear, you need a torch to get the reluctor off? Or no? What all will I need if I can pull it off with just hand tools?

Yes, I know the truck needs a whole lot more than a VSS and electric speedo and I will eventually be running a TPI and 700r4 or 4L60E, but since I have the speedo and when I get bored, I want to play with things...

The DRAC wires are as follows:

blu/blk: To speedometer 4000 PPM
ppl/white: VSS slot B
Brn: to ECM
pink/wht: 12+
blk: ground
Lt. grn/Blk: VSS slot A
Yellow (second connector, only wire): cruise control 2000 PPM

 

[HotRodPC]

I'm not aware of any Th400 with VSS provisions. You might have to use and adapter on this one. Here is a couple made by painless.

http://www.jegs.com/i/Painless/764/60115/10002/-1 Early TPI and all TBI

http://www.jegs.com/i/Painless/764/60116/10002/-1 Late TPI and Early LT

 

[bucket]

I'm not aware of any Th400 with VSS provisions. You might have to use and adapter on this one. Here is a couple made by painless.

http://www.jegs.com/i/Painless/764/60115/10002/-1 Early TPI and all TBI

http://www.jegs.com/i/Painless/764/60116/10002/-1 Late TPI and Early LT

There were th400's with the electric sender, there had to have been. A '90 3/4 ton 2wd Burb or Crew Cab for example. '90 was electric speedo.

I know a guy with a tubbed '70 Nova with a built th400 in it. It has the electric speedo sender setup on it and he was asking me how to convert it for cable speedo use. When I see him, I'll ask him if he still wants to convert. Maybe you guys can just swap.

 

[RetroC10Sport]

You could get a T400 in nearly any 1988-90 GMT400. Even 4.3 trucks.

 

[oneluckypops]

I cant remember if theres a difference in the ouput shafts or not. You may be able to just locate the reulctor ring in place of the gear on the output shaft, then either find a tailshaft from said trucks above or have your moddified to accept a VSS. Actually I am thinking that the sensor should go right into the housing you already have. Take a picture of your tail shaft (ON YOUR TRUCKS TRANSMISSION) for us.
Figured i better clearify which tail I was talking about before 89S gets excited

 

[HotRodPC]

There were th400's with the electric sender, there had to have been. A '90 3/4 ton 2wd Burb or Crew Cab for example. '90 was electric speedo.

I know a guy with a tubbed '70 Nova with a built th400 in it. It has the electric speedo sender setup on it and he was asking me how to convert it for cable speedo use. When I see him, I'll ask him if he still wants to convert. Maybe you guys can just swap.

Yes, that is true, I was thinking 90 and 90 only. 90 and 91 are squares with E speedos, but 91 4L80E was the trans in most 91's that I am aware of, so that would make the only 1. I figured for the few 90's they'd probably have stuck to the manual speedo in those models. 88 and 89 were manual speedos weren't they??? Good to know there is such thing as a VSS in a Th400 with a reluctor wheel output shaft.

 

[bucket]

Yeah, '88 and '89 were cable op. '89 was the only model with a 241 t-case and cable speedo.

Kinda wonder why they changed something every year, instead of waiting and doing it all at once.

 

[HotRodPC]

Yeah, '88 and '89 were cable op. '89 was the only model with a 241 t-case and cable speedo.

Kinda wonder why they changed something every year, instead of waiting and doing it all at once.

Those were funky years in there. 87 first year for TBI, 91 first year for 4L80-E blah blah blah. Just like the 94 and 95 year trucks. 94 has some 1 only things, 95 has some 1 only like the Transmisison, being last year of TBI, but first year for Pulse Width Modulation (PWM) so in 96 SFI Vortec (Sequential Fuel Injection) and PWM, so 95 is all on its own in the computer system for the trans.

 

[RetroC10Sport]

 

[HotRodPC]

Is that the one that's in your truck? Its got a passenger car long (wrong as the ***** would say) shaft and slip yoke. Trucks normally used short 4in shaft and bolt on yoke. Doesn't really matter though as long as your driveshaft works, and you'd have had to use slip yoke anyway. Single driveline for short bed, so the slip couldn't be in the driveshaft.

 

[davbell22602]

Is that the one that's in your truck? Its got a passenger car long (wrong as the ***** would say) shaft and slip yoke. Trucks normally used short 4in shaft and bolt on yoke. Doesn't really matter though as long as your driveshaft works, and you'd have had to use slip yoke anyway. Single driveline for short bed, so the slip couldn't be in the driveshaft.

Is that one way on telling a car auto trans apart from a truck auto trans? Are the shafts and slip yokes interchangeable from either a car or truck trany?

 

[RetroC10Sport]

Is that the one that's in your truck?

Yeah...I put about 50 miles on it today...Gawd, I need to do something about that exhaust...I've got a headache...

 

[Joeairforce]

I've seen a couple of 1989-1990 T400 GMT400s at the junkyard, but from what i hear, you need a torch to get the reluctor off? Or no? What all will I need if I can pull it off with just hand tools?

I know for the t-cases you just need a pair of snap-ring pliers (the kind with the flat blades that spread the rings) to remove the snap-ring and it just slides off the shaft..... Don't know about in the trans though.... Can't imagine it being that different though...

 

[HotRodPC]

Is that one way on telling a car auto trans apart from a truck auto trans? Are the shafts and slip yokes interchangeable from either a car or truck trany?

Yes that is one way to tell. Yes they are interchangeable too if you build the trans that way. So when I put my Olds 455 in a square, I'll use the Th400 out of the Olds that has the Variable pitch torque converter, but I'll use the short Chevy Truck output shaft and bolt on output shaft instead of the 9in car output shaft that is not tapped for bolt on yoke.

 

[RetroC10Sport]

I know for the t-cases you just need a pair of snap-ring pliers (the kind with the flat blades that spread the rings) to remove the snap-ring and it just slides off the shaft..... Don't know about in the trans though.... Can't imagine it being that different though...

Then I'll just have to take some tools with me and have a peek.